With every spacecraft that leaves Earth, millions of microbes hitch a ride into space. As astrobiologists search for life in other worlds, preventing forward and back contamination remains a key priority.

The atmosphere of the early Earth may have been filled with particulate haze, much like a smoggy day in Los Angeles. This hazy air would have affected the ancient climate and even may have influenced the origin and evolution of life.

The change in Earth´s climate may help scientists better understand planetary habitability in general. Scientists are now learning how small shifts in climate can have dramatic consequences for the planet´s environment and the life that depends on it.